We performed microarray experiments for expression profiling of Mouse Embryonic Fibroblasts of gsn -/- and wt mice and their response to Bleomycin and Staurosporin. For our purpose we used the Affymetrix MOE 430 v2.0 GeneChips which contain transcripts and variants from over 34,000 well characterized mouse genes. Total RNA was collected from mouse embryonic fibroblasts isolated from wt and gsn -/- embryos at E13.5 . MEFs were either treated with Staurosporin (250nM) for 4h or Bleomycin (60ìg/ml) and Saline for 24h. RNA extraction was performed after cell harvesting and resuspension in Trizol™ .Two Test3 GeneChip® Arrays were utilized to determine the quality of a labeled target prior to its analysis with the GeneChip® expression arrays. Microarray analysis was performed with these six samples in single color experiments. After normalization, and data import to database, differential expressed genes were selected from each condition group (wt or gsn-/-) according to their fold change (FC>=2) relative to the saline treatment for each of the two groups respectively. Further selection identified 429 probesets and of those 110 probesets were reverse regulated between the different conditions. Pearson cluster analysis was carried out in both sets which was followed by data mining on Gene ontology, KEGG pathways and InterPro common protein motifs. Knockout of the gelsolin gene was found to play a critical role in immune response, enzymatic activity, and membrane structural changes.